Get even! Producing a nice even color with your coloring pencil is all down to pressure. Push harder on your page for darker coloring, applying little pressure will producer a much lighter color. It is tempting to put lots of pressure on the pencil to produce the darkest color _ don't do it! Too much pressure will likely cause you to break your pencil leads, produce a scratchy finish to your coloring and give you less control. Instead, try applying your pencil with a little less pressure and use small circular motions with the pencil to get an even finish.
Then you can also create a texture effect. Just cover the drawing with a light stroke first then follow with rough, think strokes to serve as details . texture. This can also be applied when you're using colored pencils. And you can also create a light, smooth look with crayons. Just color your drawing with very rough and thick strokes (this might make the drawing look messy at first) then rub off the excess color with cotton or scratch paper.